TY  - JOUR
A1  - Welden, Rene
A1  - Jablonski, Melanie
A1  - Wege, Christina
A1  - Keusgen, Michael
A1  - Wagner, Patrick Hermann
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
T1  - Light-Addressable Actuator-Sensor Platform for Monitoring and Manipulation of pH Gradients in Microfluidics: A Case Study with the Enzyme Penicillinase
JF  - Biosensors
N2  - The feasibility of light-addressed detection and manipulation of pH gradients inside an electrochemical microfluidic cell was studied. Local pH changes, induced by a light-addressable electrode (LAE), were detected using a light-addressable potentiometric sensor (LAPS) with different measurement modes representing an actuator-sensor system. Biosensor functionality was examined depending on locally induced pH gradients with the help of the model enzyme penicillinase, which had been immobilized in the microfluidic channel. The surface morphology of the LAE and enzyme-functionalized LAPS was studied by scanning electron microscopy. Furthermore, the penicillin sensitivity of the LAPS inside the microfluidic channel was determined with regard to the analyte’s pH influence on the enzymatic reaction rate. In a final experiment, the LAE-controlled pH inhibition of the enzyme activity was monitored by the LAPS.
KW  - microfluidics
KW  - enzyme kinetics
KW  - actuator-sensor system
KW  - light-addressable electrode
KW  - light-addressable potentiometric sensor
Y1  - 2021
U6  - http://dx.doi.org/10.3390/bios11060171
SN  - 2079-6374
N1  - This article belongs to the Special Issue "Selected Papers from the 1st International Electronic Conference on Biosensors (IECB 2020)"
VL  - 11
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Miyamoto, Ko-Ichiro
A1  - Sato, Takuya
A1  - Abe, Minami
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
A1  - Yoshinobu, Tatsuo
T1  - Light-addressable potentiometric sensor as a sensing element in plug-based microfluidic devices
JF  - Micromachines
N2  - A plug-based microfluidic system based on the principle of the light-addressable potentiometric sensor (LAPS) is proposed. The LAPS is a semiconductor-based chemical sensor, which has a free addressability of the measurement point on the sensing surface. By combining a microfluidic device and LAPS, ion sensing can be performed anywhere inside the microfluidic channel. In this study, the sample solution to be measured was introduced into the channel in a form of a plug with a volume in the range of microliters. Taking advantage of the light-addressability, the position of the plug could be monitored and pneumatically controlled. With the developed system, the pH value of a plug with a volume down to 400 nL could be measured. As an example of plug-based operation, two plugs were merged in the channel, and the pH change was detected by differential measurement.
KW  - light-addressable potentiometric sensor
KW  - plug-based microfluidic device
KW  - chemical sensor
Y1  - 2016
U6  - http://dx.doi.org/10.3390/mi7070111
SN  - 2072-666X
N1  - This article belongs to the Special Issue "Micro/Nano Devices for Chemical Analysis"
VL  - 7
IS  - 7
SP  - 111
PB  - MDPI
CY  - Basel
ER  -